There are a couple of places where the tuners can loosen up.
Check the mounting nut first. It should be snug. When the wood shrinks in dry weather, these can get loose. If you have to tighten this nut, don't make it too tight, just snug or slightly past snug.
The next place tuners can loosen up is at the tension screw. That's the little allen screw at the end of the worm gear. I don't recall offhand the size of wrench but it would be 1.5 mm or 2.0 mm. As you tighten this screw make sure the wrench is fully engaged as small screws like this strip easily. You'll know if this screw is loose by the feel of the tuner with the string removed. If the tuner feels loose and sloppy, it needs to be adjusted. If it feels smooth with a slight amount of resistance when turned, you're good. If it feels stiff to turn, you need to back off the tension.
The last place to look is the tuner button itself. The button is press fit onto the worm gear shaft. If you wiggle the button, you shouldn't be able to detect any movement of the button on the shaft. If there is movement, I recommend taking it to a tech for them to inject either some thin CA glue into the joint or pull the button off, add a little bit of epoxy or JB weld then press back on. If your bass is less than a year old, contact tech at dingwall guitars dot com and we'll arrange to send you a replacement.